Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
int H,W;
int ans;
char s[51][51];
int a[51][51];
int dx[4]={1,0,-1,0};
int dy[4]={0,-1,0,1};
int bfs(){
  queue<int> q,q2;
  q.push(0);
  q2.push(0);
  a[0][0]=0;
  while(!q.empty()){
    int yy=q.front(),xx=q2.front();
    q.pop();q2.pop();
    for(int i=0;i<4;i++){
      int ny=yy+dy[i],nx=xx+dx[i];
      if(0<=nx && nx<W && 0<=ny && ny<H && s[ny][nx]=='.' && a[ny][nx]==-1){
	a[ny][nx]=a[yy][xx]+1;
	q.push(ny);q2.push(nx);
      }
    }
  }
  return a[H-1][W-1];
}
int main(){
  cin >> H >> W;
  ans=H*W-1;
  for(int i=0;i<H;i++)cin >> s[i];
  for(int i=0;i<H;i++){
    for(int j=0;j<W;j++){
      a[i][j]=-1;
      if(s[i][j]=='#'){a[i][j]=0;ans--;}
    }
  }
  int x=bfs();
  if(x==-1)cout << "-1" << endl;
  else cout << ans-x << endl;

  
 
  return 0;
}